Gas burner



April 13, 1965 P. HINE, JR.. ETAL 3,177,923

- GAS BURNER Filed Nov. 27, 1961 2 Sheets-Sheet 2 1 INVENTORS. LOU/6 RSH/NE J2. By? RIC/442D J. VALES JMY/ Kama/{KW ATTOENEYS.

United States Patent 3,177,923 GAS BURNER Louis P. Hine, 3n, and Richard J. Vales, Elyria, Qhro, assignors to The C. A. Olsen Mfg. Co., Elyria, Uhro Filed Nov. 27, 1961, Ser. No. 155,015 Claims. ((31. 158-116) This invention relates to gas heating and particularly to gas burners for furnaces.

It is an object of the invention to obtain increased efiiciency and improved characteristics of combustion of fuel gases.

A further object of the invention is the incineration of entrained lint, the prevention of clogging of gas burners, elimination of flashback, simplification and reduction of costs of construction of durable, sturdy gas burners of light weight, which are safe in operation.

Still another object is to provide a universal burner suitable for any type of gas.

Other and further objects, features and advantages of the invention will become apparent as the description proceeds.

In carrying out the invention in accordance with a preferred form thereof, an elongated horizontal burner is provided which is fabricated from sheet material such as carbon steel or other cold rolled steel to form a mixing tube tapering to a relatively small closed end with an open top closed by a burner strip having elongated slots therein. Preferably the burner strip is composed of material such as chrome type stainless steel, which is not corroded by sulfur-containing gases and withstands high temperatures, permitting use as a universal burner for any type gas. The slots are relatively long, but of considerably less length than the extent of the mixing tube so as to provide enough webs, or material between successive slots in the same row, for adequate structural strength. The use of noncorrosive strip material prevents alteration of slot size or contour in event of contact with corrosive gas. The burner strip is composed of relatively thin gage stock so as to maintain a relatively high temperature on the inner surface of the burner strip. Nevertheless, there is a high temperature difference between the slots and the edge of the strip so that the mixing tube runs cool. The slots are as narrow or narrower than the thickness of the burner strip and flashback tendency is avoided even for relatively fast flame propagation gases, such as manufactured gas and propane gas.

In operation any lint in the atmosphere is entrained in the column of mixed air and combustible gas travelling lengthwise in the mixer tube. The burner strip forms a zone of high temperature difference between slot edges and the mixer tube. Lint carried upwardly toward the slots from the air and gas column in the streams of mixed air and gas is incinerated when it comes in contact with the hot burner strip. Ignition of the air-gas mixture on the outer side of the zone formed by the burner strip produces incinerating temperature on the inner side so that lint is incinerated, leaving only a light ash which can travel through the ports without clogging.

A better understanding of the invention will be afforded by the following detailed description considered in conjunction with the accompanying drawing, in which:

FIG. 1 is an elevation of a furnace burner forming an embodiment of the invention;

FIG. 2 is a plan view of the burner of FIG. 1;

FIG. 3 is a view of a cross-section of the burner of FIGS. 1 and 2, represented as cut by a plane 33, indicated in FIG. 1;

FIG. 4 is a view of a section of the burner of FIG. 1 cut by a plane 4-4 passing through the Venturi throat thereof with the remaining structure omitted for clarity;

FIG. 5 is an end view of the burner of FIG. 1 showing the arrangement of the air mixture control shutter;

FIG. 6 is a fragmentary plan view of a burner strip with modified slot arrangement, which may be used in a gas burner of the general construction illustrated in FIGS. 1 and 2;

FIG. 7 is an end View. of the burner strip of FIG. 6;

FIG. 8 is a fragmentary view of a burner strip forming another embodiment of the invention;

FIG. 9 is a fragmentary view of a finned burner strip forming still another embodiment of the invention;

FIG. 10 is a view of a cross-section of the burner strip of FIG. 9, represented as cut by a plane 1010, indicated in FIG. 9;

FIG. 11 is a fragmentary broken side elevation of the finned burner strip of FIG. 9;

FIG. 12 is a plan view of a finned burner strip constituting still another embodiment of the invention; and

FIG. 13 is a view of a section of the burner strip of FIG. 12, represented as cut by a plane 13-13, indicated in FIG. 12.

Like reference characters are utilized throughout the drawing to designate like parts.

The burner illustrated in FIGS. 1 to 5 of the drawing comprises a mixing tube 11 having a relatively small closed end 12 and an open end 13 with a Venturi throat 14. The open end 13 is of relatively large diameter to receive a conventional rotatable shutter 15 for controlling the ratio of air to gas in the mixture admitted to the mixing tube 11, having a conventional center opening 16 into which the nipple of a gas pipe (not shown) projects.

The diameter of the mixing tube 11 increases from the Venturi throat portion 14 to a point 17 of maximum diameter, after which it again tapers to a relatively small diameter at the end 12. As shown in FIG. 3, the portion of the mixing tube 11 between the maximum diameter point 17 and the end 12 has a longitudinally extending lateral opening 18 covered by a burner strip 19. In this embodiment of the invention, long, narrow slots 21 in a plurality of rows with the slots staggered in successive rows are provided in the burner strip 19 to form ports from which separate streams of air-gas mixture issue to form the flame. Preferably the portion of the material forming the tube 11 adjacent the lateral opening 18 is bent transversely outward to form ribs 22 for spacing the burner strip 19 from the remainder of the mixing tube 11. The burner strip 19 is joined to the edge of the ribs 22 in any suitable manner to form a gas-tight joint. Preferably, as shown, the edges 23 of the ribs22 are bent at right angles and the edges 24 of the burner strip 19 are crimped around the edge portions 23.

In order to achieve low manufacturing costs, durability and lightness, the mixing tube 11 is preferably fabricated from two pieces of sheet'material such as pieces 25 and 26 composed of cold-rolled, carbon-steel sheet. The pieces 25 and 26 are stamped or pressed to shape to form a frusto-conical cavity 31 in the central portion of the two sheets 25 and 26 to form the hollow mixing tube interior with flat side portions 27 and 23 below, flat side portions 29 and 3% above from the end 13 to the maximum diameter opening portion 17 and the ribs 22 above from the maximum diameter opening portion 17 to the closed end 12. The end 12 is closed by an upwardly extending flattened portion 32. The flattened portions 27, 28, 29 V and 3% are joined in any suitable manner as by means of crimped over edges 33, as shown.

In the embodiment illustrated in FIGS. 2 and 3 the slots 21 consist of three rows of slots, each row consisting of sixteen or seventeen slots in alignment. The invention is not limited to specific dimensions, but in the Patented Apr. 13, I965v provides the greater'strength. To avoid distortion of slot width, we believe that thinner strips will require shorter slots, and greater web dimension than thicker strips; Generally the optimum slot length is approximately ten or more times the slot width for most eflicient operation.

The sheet material comprising the pieces 25 and 26 is smooth surfaced and preferably coated with a smooth lacquer or other coating material. Consequently, lint drawn into the openings of the shutter assembly 15. from the air tends not to adhere to the inner surfaces of the mixing tube 11 and clogging of the interior 31 does not occur. However, lint tends to be drawn to the ports in the burner strip 19. As will be explained more fully hereinafter, the lint is incinerated at the ports and port clogging does not occur. When the ports 21 are punched, they may be punched from the inner surface of the strip 19 toward the outer surface in order to avoid forming a bur on the inner surface which might catch lint or arrest its progress to the port opening and point of maximum temperature for disintegration.

The burner strip 19 is composed of thin material as described so that the inner surface runs substantially as hot as the outer surface as a result of the flames issuing from the ports 21. Moreover, the material of which the strip 19 is composed preferably has a heat conductivity as low or lower than that of the carbon steel tube 11 so that there is a high temperature gradient between the slots or ports 21 and the edges 24 of the burner strip 19. Thus, the tube 11 runs relatively cool, notwithstanding the high temperature of the slot portion of the burner strip 19 at the base of the flame. A suitable material for the burner strip 19 has been found to be stainless steel, particularly the chromium type of stainless steel which is not corroded when exposed to sulfur-bearing gases and will withstand higher temperature than carbon steel. This is especially important when LP or manufactured gas is used which may have .a flame temperature of about 1200 F., not far from the critical temperature for carbon steel. Heat resisting steel, however, minimizes grain growth and therefore minimizes permanent deformation. It also has a somewhat lower heat conductivity than carbon steel. In the embodiment, illustrated, the burner strip 19 is composed of twenty gage stainless steel, which is approximately .035 inch in thickness. Such thin strip runs very hot at the lower surface immediately adjacent the slot 21 and causes incineration of any lint drawn to the slot 21.

As explained more fully hereinafter, where only two rows of slots or ports are provided a heater fin may be utilized for increasing temperature of the burner strip. We have found, however, that with three rows of ports the flame is brought down close to the ports to increase temperature of the burner strip and obtain satisfactory incineration of lint. The arrangement permits delivering sufficient gas to generate 25,000 B.t.u.s an hour for each square inch of port area without blowing the flame away from the port as well as permitting greatly reduced gas delivery without flashback.

For preventing flashback even with fast burning gases with a high rate of flame propagation such as manufactured gas having high percentage of hydrogen, the slots 21 are made narrow, being no wider than the thickness of the strip 19, preferably slightly less, for example, .030 inch in the case of twenty gage stainless steel strip. Consequently, the burner is adapted to all usual fuel gases inciuding natural gas, mixed gases, manufactured gas, LP gas. Moreover, it is unnecessary to employ drilled ports or ports having long bore or axial length in order to cause the rate of gas flow to be greater than the rate of flame propagation. We have found that it is the maximum width of the port rather than the cross-sectional area of the port which determines the susceptability to flashback.

In order to permit use of one pilot burner for several adjacent burners, each burner may be provided with a can", -over device 35 which overhangs an end port for transferring flame to an adjacent burner to ignite it.

Although in the embodiment of FIGS. -1 to 5 staggered slots of equal length have been described and illustrated, it will be understood that the invention is not limited thereto and if desired, as shown in FIG. 7, a central row of slots 36 may be employed of shorter length than the outer rows of slots; or as illustrated in FIG. 8, slots 37 may be employed of equal length and aligned crosswise as well as lengthwise.

Although by way of example, constructions had been described having three rows of slots, it will be understood that the invention is not limited to a specific number of rows of slots and does not exclude a construction having more or less rows, including a construction as in FIGS. 9 and 12, for example, having two rows of slots. Moreover, if desired, means may be provided for increasing the temperature of the burner strip 39 immediately adjacent the slots 38 for enhancing the incineration of lint which may be drawnto the under surface of the slots 33. As illustrated in FIG. 10, a burner strip 39 is employed fabricated of two strips with cent up edges 41, having a heater fin 42 between the strip portions 41 and joined thereto in a suitable manner as by welding, for example.

The heat of the flame issuing from the slot 38 impinges upon the fin 42 to elevate the temperature thereof causing likewise a relatively high temperature of the strip 39 adjacent the slots 38. In the form of burner illustrated in FIG. 11, the tin 42 is tapered to a lower height at th smaller end 12 of the tube to control port temperature precisely.

It will be understood, however, that the invention is not limited to the use of a separate heater fin 42. For example, an integral heater fin 43 may be formed in a burner strip 44 of sufficient Width to allow for bending up a central portion doubled back as illustrated in FIG. 13 to form the integral fin 43. Milled or sawed or punched slots have been illustrated in FIGS. 2, 3, 6, 8 and 9, but it will be understood that the invention is not limited thereto and if desired lanced slots 45 may be utilized as illustrated in FIGS. 12 and 13. The lanced slots 45 are formed by striking up portions of the material of the burner strip 44 to form deflectors 46 which direct the isitrejgn of gas issuing from the slots 45 against the heater Certain embodiments of the invention and certain methods of operation embraced therein have been shown and particularly described for the purpose of explaining the principle of operation of the invention and showing its application, but it will be obvious to those skilled in the art that many modifications and variations are possible, and it is intended, therefore, to cover all such modifications and variations as fall within the scope of the invention.

What is claimed is:

1. A lint free gas burner comprising a mixing tube havmg an open end for-entry of gas and air and having a portion of flat configuration lying in a plane, wherein the flat portion is formed as a burner strip with two longitudinal areas and with slots in each and a heater fin is provided between'the two areas for elevating the temperature of the slotted portion of the burner strip.

2. A lint free gas burner as in claim 1, wherein the burner strip is fabricated with transversely bent center 5 portions and the heater fin constitutes a strip of sheet material between said transversely bent portions joined thereto.

3. A gas burner as in claim 1, wherein the heater fin constitutes a folded up central portion of the burner strip and the heater fin is integral with the remainder of the burner strip.

4. A burner as in claim 3, wherein the slots constitute lanced ports on either side of the heater fin.

5. A lint free gas burner comprising a mixing tube having a gas inlet and an elongated opening, and a burner strip across said opening composed of sheet metal of the order of .035 inch in thickness having elongated parallel slots therein of the order of .03 inch in width and over 0.3 inch in length.

References Cited by the Examiner UNITED STATES PATENTS 2,638,976 5/53 Vixler 158-116 2,701,610. 2/55 Carlson 158-104 FOREIGN PATENTS 42,777 10/ 33 France. 705,778 6/31 France. 936,418 7/ 48 France.

1,393 12/97 Great Britain. 150,246 9/20 Great Britain.

JAMES W. WESTHAVER, Primary Examiner.

6 PERCY L. PATRICK, Examiner. 

5. A LINT FREE GAS BURNER COMPRISING A MIXING TUBE HAVING A GAS INLET AND AN ELONGATED OPENING, AND A BURNER STRIP ACROSS SAID OPENING COMPOSED OF SHEET METAL OF THE ORDER OF .035 INCH IN THICKNESS HAVING ELONGATED PARALLEL SLOTS THEREIN OF THE ORDER OF .03 INCH IN WIDTH AND OVER 0.3 INCH IN LENGTH. 